Tap dual port router with update lead and gated updatedr

ABSTRACT

This disclosure describes a test architecture that supports a common approach to testing individual die and dies in a 3D stack arrangement. The test architecture uses an improved TAP design to facilitate the testing of parallel test circuits within the die.

REFERENCE TO RELATED DISCLOSURES

This Application is a Divisional of prior application Ser. No.15/340,507, filed Nov. 1, 2016, now U.S. Pat. No. 9,753,085, issued Sep.17, 2017;

Which was a divisional of prior application Ser. No. 14/978,752, filedDec. 22, 2015, now U.S. Pat. No. 9,513,336, issued Dec. 6, 2016;

Which was a divisional of prior application Ser. No. 14/547,830, filedNov. 19, 2014, now U.S. Pat. No. 9,261,559, issued Apr. 16, 2016;

Which was a divisional of prior application Ser. No. 13/587,522, filedAug. 16, 2012, now U.S. Pat. No. 8,924,802, issued Dec. 30, 2014;

And claims priority from Provisional Application No. 61/524,632, filedAug. 17, 2011.

This disclosure is related to pending application Ser. No. 13/188,078and U.S. Pat. Nos. 7,404,129 and 7,346,821.

FIELD OF THE DISCLOSURE

This disclosure relates generally to three dimensional (3D) stacked dieand specifically to a test architecture that supports the testing of diein the 3D stack.

BACKGROUND OF THE DISCLOSURE

Integrated circuit die may be designed such that they may be stacked ontop of one another to form a stacked die arrangement for mounting on asystem substrate, such as, but not limited to, a printed circuit board.Prior to assembling a stacked die, each die to be stacked must be testedto ensure goodness. After a stacked die is assembled, it must be testedagain to ensure the goodness of the assembly.

Testing of the individual die is typically done by a die tester. Testingof the stacked die assembly is typically done by a stacked die assemblytester. The test architecture designed into the die must be capable ofsupporting both the testing of the individual die on the die tester andthe testing of the final stacked die assembly on the stacked die tester.The present disclosure describes a test architecture that supports bothindividual die testing and final stacked die assembly testing.

BRIEF SUMMARY OF THE DISCLOSURE

This disclosure describes a test architecture that supports the testingof individual die and 3D stacked die arrangements.

BRIEF DESCRIPTIONS OF THE VIEWS OF THE DRAWINGS

FIG. 1 illustrates an IEEE Test Access Port (TAP).

FIG. 2 illustrates the state diagram of the TAP.

FIG. 3 illustrates a TAP capture and shift operation.

FIG. 4 illustrates a TAP capture, shift and update operation.

FIG. 5 illustrates an improved TAP design of the disclosure.

FIG. 6 illustrate a dual port router (DPR) of the disclosure.

FIG. 7 illustrate an improved TAP capture and shift operation.

FIG. 8 illustrate a DPR of the disclosure.

FIG. 9 illustrate an improved TAP capture, shift and update operation.

FIG. 10 illustrates a test architecture of the disclosure.

FIG. 11 illustrate stacked die using bond wires.

FIG. 12 illustrates stacked die using through silicon vias (TSVs).

FIG. 13A illustrates a test architecture of the disclosure.

FIGS. 13B-13E illustrates various test control signal gating circuits ofthe disclosure.

FIG. 14 illustrates a test architecture of the disclosure.

FIG. 15 illustrates a die stack according to the disclosure.

FIG. 16 illustrates a die stack according to the disclosure.

FIG. 17 illustrates a test architecture of the disclosure.

FIG. 18 illustrates test circuit of the disclosure.

FIG. 19 illustrates a compare circuit of the disclosure.

FIG. 20 illustrates a maskable compare circuit of the disclosure.

FIG. 21 illustrates a test architecture of the disclosure.

FIG. 22 illustrates a die stack according to the disclosure.

FIG. 23 illustrates a test architecture of the disclosure.

FIG. 24 illustrates a test architecture of the disclosure.

FIG. 25 illustrates a test architecture of the disclosure.

FIG. 26 illustrates a multiple TAP Domain architecture of thedisclosure.

FIG. 27 illustrates a die stack according to the disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

FIG. 1 illustrates a die 100 including a conventional IEEE 1149.1 testarchitecture. The architecture includes a TAP State Machine (TSM), aninstruction register 104, data registers 1-N 106 including a bypassregister and boundary register, TDO multiplexer circuitry 108 and arouter for navigating control signals from the TSM to a target dataregister. The die has inputs for a TDI, TCK and TMS signal and an outputfor a TDO signal. The TSM inputs the TCK and TMS signals, and outputsdata register control (DRC) to the router, instruction register control(IRC) to the instruction register and a Select signal to the TDOmultiplexer circuitry. The instruction register inputs the TDI signaland the IRC signals and outputs control on an instruction registeroutput (IRO) bus and a TDO signal to the TDO output via the TDOmultiplexer. Each data register inputs the TDI signal, DRC inputs fromthe router and outputs a TDO signal to the TDO output via the TDOmultiplexer. During instruction scan operations, the TSM controls theinstruction register to capture instruction data, shift instruction datafrom TDI to TDO and update the instruction data from the instructionregister. During data scan operations the TSM controls a data registerselected by the current instruction to capture data, shift data from TDIto TDO and update data from the data register.

FIG. 3 illustrates a first example router circuit 110 that can beenabled by the IRO bus to control capture and shift operations to a dataregister 106. In this example, the router circuit couples ClockDR andShiftDR signals 302 from the DRC output bus of TSM 102 to ClockDR andShiftDR signals 304 to the DRC input bus of the data register, viagating circuits 308 and 310. The ClockDR provides the clock input to thedata register and the ShiftDR signal provides the capture or shift inputto the data register. The repeating TSM state transitions 306 to accessthe data register is indicated in FIG. 3. As shown there are dead states(dotted line box states) in the repeating TSM state transitions. Forexample, there are 3 dead states between the last ShiftDR operation andthe CaptureDR operation. This prevents the TSM from being able toperform at speed shift and capture operations. This is a well known TSMtesting limitation.

FIG. 4 illustrates a second example router circuit 110 that can beenabled by the IRO bus to control capture, shift and update operationsto a data register 106. In this example, the router circuit couplesClockDR, ShiftDR and UpdateDR signals 402 from the DRC output bus of TSM102 to ClockDR, ShiftDR and UpdateDR signals 404 to the DRC input bus ofthe data register, via gating circuits 408-412. The ClockDR provides theclock input to the data register, the ShiftDR signal provides thecapture or shift input to the data register and the UpdateDR signalprovides the update input to the data register. The repeating TSM statetransitions 406 to access the data register is indicated in FIG. 4. Asshown there are dead states (dotted line box states) in the repeatingTSM state transitions. For example, there is a dead state between thelast ShiftDR operation and the UpdateDR operation and another dead statebetween the UpdateDR operation and the CaptureDR operation. Thus atspeed shift and update operations and at speed update and captureoperations cannot be performed using TSM state transitions. This is awell known TSM testing limitation.

The following disclosure provides a die test architecture that includesan improved TAP in combination with a parallel test input and outputmechanism for facilitating the testing of functional circuits within thedie.

FIG. 5 illustrates a die 500 including the improved TAP architecture ofthe disclosure. The TAP architecture is identical to the TAParchitecture of FIG. 1 with the exception that the router 102 of FIG. 1has been replaced with a dual port router (DPR) 502. The TAParchitecture of FIG. 5 also includes two new inputs, a Capture (CPT)input and an Update (UPD) input. The first input port 504 of the DPR iscoupled to the DRC outputs from the TSM and the second input port 506 ofthe DPR is coupled to the CPT and UPD inputs. The DRC outputs of the DPRare coupled to respective data registers 106. The DPR inputs IRO signalsfrom the instruction register. During instruction scan operations, theTSM controls the instruction register to capture instruction data, shiftinstruction data from TDI to TDO and update the instruction data fromthe instruction register.

During data scan operations when the IRO bus selects the first inputport 504 of the DPR, the TSM controls a data register selected by thecurrent instruction to capture data, shift data from TDI to TDO andupdate data from the data register. When the first port of the DPR isselected, the TAP architecture of FIG. 5 operates exactly like the TAParchitecture of FIG. 1. However, during data scan operations when theIRO bus selects the second input port of the DPR, the TSM controls theshifting of a selected data register between TDI and TDO, but thecapture and update operations of the data register are controlled by theCPT and UPD inputs, respectively.

FIG. 6 illustrates a first example DPR circuit 502 that can be enabledby the IRO bus to control capture and shift operations to a dataregister 106. As seen, the example DPR circuit is identical to theexample router circuit of FIG. 3 with the exception that a multiplexerhas been placed on ShiftDR input of gate 308. When the ShiftDR outputsignal of bus 304 is to be controlled by the ShiftDR input signal of bus302, the IRO input will enable the gates and will set the multiplexer toinput the ShiftDR signal from the TSM to gate 308. When the ShiftDRoutput signal of bus 304 is to be controlled by the CPT input signal,the IRO input will enable the gates and will set the multiplexer toinput the CPT signal to gate 308.

FIG. 7 illustrates the timing diagram of performing capture and shiftoperations using the CPT input. As seen the TSM will go to and remain inthe ShiftDR state (TMS=0) to cause data to shift through the dataregister from TDI to TDO. At appropriate times during the shifting theCPT signal will be asserted, to cause a capture operation to occur, thende-asserted to resume shifting. As seen, there are no dead states in thecapture and shift operations when using the CPT signal, as there were inthe FIG. 3 timing example 306.

FIG. 8 illustrates a first example DPR circuit 502 that can be enabledby the IRO bus to control capture, shift and update operations to a dataregister 106. As seen, the example DPR circuit is identical to theexample router circuit of FIG. 4 with the exception that a multiplexer804 has been placed on ShiftDR input of gate 410 and a multiplexer 802has been place on the UpdateDR input of gate 408. When the ShiftDR andUpdateDR output signals of bus 404 are to be controlled by the ShiftDRand UpdateDR inputs of bus 402, the IRO input will enable gates 408-412and will set the multiplexers to input the ShiftDR and UpdateDR signalsfrom the TSM to gates 408 and 410. When the ShiftDR and UpdateDR outputsignals of bus 404 are to be controlled by the CPT and UPD inputsignals, the IRO input will enable the gates and will set themultiplexers to input the CPT and UPD input signals gates 410 and 408.

FIG. 9 illustrates the timing diagram of performing capture, shift andupdate operations using the CPT and UPD inputs. As seen the TSM will goto and remain in the ShiftDR state to cause data to shift through thedata register from TDI to TDO. During the shifting the UPD signal willbe asserted to cause an update operation to occur, then the CPT signalwill be asserted to cause a capture operation to occur. Shifting resumesfollowing the update and capture operations. As seen, there are no deadstates in the capture, shift and update operations when using the CPTand UPD signals, as there were in the FIG. 4 timing example 306.

FIG. 10 illustrates a die 1000 containing the improved TAP architecture1002 of FIG. 5 coupled to parallel test circuits 1-N 1004 via the DRCand IRO buses of the improved TAP architecture. As seen in FIG. 10, theDRC and IRO buses of FIG. 5 are extended from the improved TAParchitecture 1002 to form connections to the parallel test circuits1004. Each parallel test circuit has a group of Parallel Test DataInputs (PTDI) and a group of Parallel Test Data Outputs (PTDO). Whenenabled by the IRO bus, a parallel test circuit may be operated by theDRC signals from the DPR to perform capture and shift operations, orcapture, shift and update operations. The IRO inputs to the DPR allowthe capture and shift or capture, shift and update operations to beselectively controlled by the TSM, as shown in FIGS. 3 and 4, or by theCPT and UPD signals, as shown in FIGS. 6-9. The advantage of using theCPT and UPD signals to control a parallel test circuit is that thecapture and shift and the capture, shift and update operations do notinclude dead states. During the shifting part of the above mentionedoperations, the parallel test circuit inputs parallel test data fromPTDI and outputs parallel test data to PTDO. During test, the PTDI andPTDO buses are coupled to external leads of die 1000, as will be shownand described in regard to FIGS. 13, 14, 16, 17, 21, 22, 23, and 24.

FIG. 11 illustrates an older approach 1100 of stacking die on top of oneanother. This example shows the stack including a bottom die, a middledie and a top die. This stacking approach is based on a pyramidarrangement where smaller die are stacked onto larger lower. The die areconnected to each other using bond wires 1102 located between bond pads1104 at the periphery of the die. While not shown each die containsfunctional circuits that are connected to the bond pads. The bottom dieof the stack is mounted on a substrate.

FIG. 12 illustrates a newer approach 1200 of stacking die on top of oneanother. This example shows the stack including a bottom die, a middledie and a top die. This stacking approach, commonly referred to as threedimensional (3D) stacking, is based on vertical connections 1202,referred to as through silicon vias (TSV), that are formed from thebottom surface of a die to the top surface of the die. When die arestacked, contact points (micro bumps) 1204 on the surfaces of each dieconnect the embedded TSVs of each die together to provide verticalsignaling paths up and down the die stack from a substrate. While notshown each die contains functional circuits that are connected to someof the TSVs. There are many advantages of using TSVs, including but notlimited too, simplification of connectivity, high bandwidth signalingand the ability to provide an extremely large number of connectionsbetween die in a stack.

While the test architecture of this disclosure may be implemented in diethat are stacked using the older pyramid approach of FIG. 11 or thenewer 3D approach of FIG. 12, this disclosure describes the testarchitecture as it would be implemented in die that are designed to bestacked using the 3D approach of FIG. 12. However, it should beunderstood that the test architecture of this disclosure is not limitedto only being used in die that are stacked according to the 3D approach.Indeed, the test architecture may be implemented in die designed to bestacked in either the pyramid approach, the 3D approach or in variousarrangements that may use a mixture of pyramid and 3D approaches.Further, the test architecture may be implemented in die that are notnecessarily intended to be stacked, i.e. a standalone die.

FIG. 13A illustrates a test architecture of the disclosure designed intoa die 1300 that is to be used as the bottom die in a 3D stack diearrangement. The test architecture includes the Improved TAP 1002 andparallel test circuits 1004 of FIG. 10, gating circuitry 1306, 3-statebuffers 1302, and multiplexer 1304. The die includes an N signal widebus of PTDI TSVs 1202 extending from contact points 1204 on the bottomsurface of the die to contact points 1204 on the top surface of the die.The die includes a bus of Test Control Input (TCI) TSVs 1202, includingthe CPT, UPD, TCK and TMS signals of FIG. 10, that are coupled betweencontact points 1204 on the bottom surface of the die to contact points1204 on the top surface of the die. The die includes a TDI contact point1204 on the bottom surface of the die for inputting a TDI signal to theImproved TAP. The die includes a TDO contact point on the bottom surfaceof the die for outputting a TDO signal from multiplexer 1304. The dieincludes a bus of PTDO TSVs 1202 extending from contact points 1204 onthe top surface of the die to contact points 1204 on the bottom topsurface of the die. The die includes a TDI contact point 1204 on the topsurface of the die for inputting a TDI signal to multiplexer 1304. Thedie includes a TDO contact point 1204 on the top surface of the die foroutputting a TDO signal from the Improved TAP 1002. For the bottom dieof FIG. 13, the term “bottom surface” means the die surface to becoupled to a system substrate, and the term “top surface means the diesurface to be connected to an upper die in the stack.

Gating circuit 1306 has inputs coupled to some or all of the TCI contactpoints on the bottom surface of the die, a Link input from the IRO fromthe Improved TAP and outputs coupled to some or all the TCI contactpoints on the top surface of the die. Any TCI signals that are notrouted through the gating circuit simply bypass the gating circuit asshown in dotted line.

FIG. 13B illustrates a gating circuit 1306 that gates all the TCI CPT,UPD, TCK and TMS signals.

FIG. 13C illustrates a gating circuit 1306 that gates only the TMS andTCK signals.

FIG. 13D illustrates a gating circuit 1306 that gates only the TMSsignal.

FIG. 13E illustrates a gating circuit 1306 that gates only the TCKsignal.

As seen in all gating examples of FIGS. 13B-13E, at least one or both ofthe TCK and TMS signals may be gated off. When one or both of the TCKand TMS signals are gated off, TAPs in upper die that are connected tothe TCI bus are disabled from operating.

The multiplexer 1304 inputs the TDO from the Improved TAP, the TDI inputfrom the top surface contact point, a control signal from the IRO bus ofthe Improved TAP and outputs a TDO signal to the bottom surface contactpoint.

Each Parallel Test Circuit 1004 inputs a bus of N or less than N PTDIsignals from the N wide PTDI TSV bus 1202 from a tester, the DRC busfrom the Improved TAP, optionally the IRO bus from the Improved TAP, andoutputs a bus of N or less than N PTDO signals to buffers 1302. Thebuffers, when enabled by the IRO output of the Improved TAP, output theN or less than N PTDO signals to the N wide PTDO TSV bus 1202 to thetester. The PTDI and PTDO buses may be dedicated for communicating testsignals or they may be shared between communicating test signals andfunction signals. The N width of the PTDI and PTDO buses is establishedby the Parallel Test Circuit 1004 having the widest parallel test inputand parallel test output. For example, if a Parallel Test Circuit 1004has a 32 bit parallel test input and 32 bit parallel test output, N willbe set to 32 bits.

The Improved TAP has CPT, UPD, TMS and TCK inputs coupled to the TCI TSVbus, a TDI input coupled to the bottom surface TDI contact point, a TDOoutput coupled to the multiplexer, DRC outputs coupled to the ParallelTest Circuits and IRO outputs coupled to buffer 1302 and optionally tosome or all of the Parallel Test Circuits.

When access to only the Improved TAP of die 1300 is required, the Linksignal to gating circuit 1306 is set to gate off the TCI inputs to thetop surface TCI contact points, and the control signal to multiplexer1304 is set to select the TDO output of the Improved TAP to be output onthe bottom surface TDO contact point. In this configuration, a scan pathis formed from the bottom surface TDI contact point of die 1300, throughthe Improved TAP of die 1300 and to the bottom surface TDO contact pointof die 1300, via multiplexer 1304.

When access to the Improved TAP of die 1300 and a TAP or an Improved TAPof an upper die is required, the Link signal to gating circuit 1306 isset to gate on the TCI inputs to the top surface TCI contact points, andthe control signal to multiplexer 1304 is set to select the top surfaceTDI contact point to be output on the bottom surface TDO contact point.In this configuration, a scan path is formed from the bottom surface TDIcontact point of die 1300, through the Improved TAP to the top surfaceTDO contact point of die 1300, through the TDI to TDO path of the upperdie TAP and back to the top surface TDI contact point of die 1300 andthrough multiplexer 1304 to the bottom surface TDO contact point of die1300.

When a Parallel Test Circuit 1004 is to be tested, the Improved TAP willbe loaded with an instruction that enables the buffers 1302 associatedwith the Parallel Test Circuit to be tested to drive the PTDO TSV bus.Other buffers 1302 will not be enabled. Also, and only if required, theinstruction will output IRO signals to the Parallel Test Circuit to setup its test operation mode. After this step, the Improved TAP willcontrol the Parallel Test Circuit with the DRC outputs to performcapture and shift type testing or capture, shift and update type testingas described in FIG. 10. When a Parallel Test Circuit is being tested,its PTDO outputs will be the only outputs driving the PTDO TSV bus of asingle die or a stack of die.

FIG. 14 illustrates a test architecture of the disclosure designed intoa die 1400 that is to be used as a middle or a top die in a 3D stack diearrangement. The test architecture includes the Improved TAP 1002,parallel test circuits 1004, 3-state buffers 1302, and a Fuse 1402. Thedie includes an N signal wide bus of PTDI TSVs 1202 extending fromcontact points 1204 on the bottom surface of the die to contact points1204 on the top surface of the die. The die includes a bus of TestControl Input (TCI) TSVs 1202, including the CPT, UPD, TCK and TMSsignals of FIG. 10, that are coupled between contact points 1204 on thebottom surface of the die to contact points 1204 on the top surface ofthe die. The die includes a TDI contact point 1204 on the bottom surfaceof the die for inputting a TDI signal to the Improved TAP. The dieincludes a TDO contact point on the bottom surface of the die foroutputting a TDO signal. The die includes a bus of PTDO TSVs 1202extending from contact points 1204 on the top surface of the die tocontact points 1204 on the bottom top surface of the die. The dieincludes a TDI contact point 1204 on the top surface of the die forinputting a TDI signal. The die includes a TDO contact point 1204 on thetop surface of the die for outputting a TDO signal from the Improved TAP1002. The die includes a Fuse 1402 having a first terminal connected tothe TDO output of the Improved TAP and the top surface TDO contact pointand a second terminal connected to the top surface TDI contact point andthe bottom surface TDO contact point.

For the middle or top die of FIG. 14, the term “bottom surface” meansthe die surface to be coupled to a lower or the bottom die of the stack,and the term “top surface” means the die surface to be connected to anupper middle or the top die in the stack.

Each Parallel Test Circuit 1004 inputs a bus of N or less than N PTDIsignals from the N wide PTDI TSV bus 1202, the DRC bus from the ImprovedTAP, optionally the IRO bus from the Improved TAP, and outputs a bus ofN or less than N PTDO signals to buffers 1302. The buffers, when enabledby the IRO output of the Improved TAP, output the N or less than N PTDOsignals to the N wide PTDO TSV bus 1202. The PTDI and PTDO buses may bededicated for communicating test signals or they may be shared betweencommunicating test signals and function signals. The N width of the PTDIand PTDO buses is established by the Parallel Test Circuit 1004 havingthe widest parallel test input and parallel test output. For example, ifa Parallel Test Circuit 1004 has a 32 bit parallel test input and 32 bitparallel test output, N will be set to 32 bits.

The Improved TAP 1002 has CPT, UPD, TMS and TCK inputs coupled to theTCI TSV bus, a TDI input coupled to the bottom surface TDI contactpoint, a TDO output coupled to the Fuse 1402 and the top surface TDOcontact point, DRC outputs coupled to the Parallel Test Circuits and IROoutputs coupled to buffers 1302 and optionally to some or all of theParallel Test Circuits.

Fuse 1402 is an important aspect of the present disclosure, as is allowsthe die 1400 to be programmed for use as either a middle die in a stackof die, or as the top die in a stack of die. This allows a diemanufacturer to design and manufacture only one version of a die that acustomer may purchase and chose to use it as either a middle die in thestack or the top die in the stack. The choosing is simply accomplishedby keeping the Fuse 1402 closed as it was manufactured so that the diecould be used as a top die in the customer's die stack, or by openingthe Fuse so that the die could be used as a middle die in the customer'sdie stack. The opening of the Fuse could be done in a myriad of ways,grounding the top surface TDO contact point and apply a voltagesufficient to blow the Fuse at the bottom surface TDO contact point. Theopening and closing of Fuse 1402 could be reversible if an electricallyprogrammable fuse were used. While the word Fuse is used, it should beunderstood, element 1402 could be any type of circuit or connection thatcan pass the TDO signal or not pass the TDO signal. For example, element1402 could be a 3-state buffer that is selectively enabled to pass theTDO signal or disabled to not pass the TDO signal.

When a Parallel Test Circuit 1004 is to be tested, the Improved TAP willbe loaded with an instruction that enables the buffers 1302 associatedwith the Parallel Test Circuit to be tested to drive the PTDO TSV bus.Other buffers 1302 will not be enabled. Also, and only if required, theinstruction will output IRO signals to the Parallel Test Circuit to setup its test operation mode. After this step, the Improved TAP willcontrol the Parallel Test Circuit with the DRC outputs to performcapture and shift type testing or capture, shift and update type testingas described in FIG. 10. When a Parallel Test Circuit is being tested,its PTDO outputs will be the only outputs driving the PTDO TSV bus of asingle die or a stack of die.

When the Improved TAP receives TCK and TMS control from the TCI bus itcan shift data from the bottom surface TDI contact point to the topsurface TDO contact point. If the Fuse 1402 is closed, the data shiftedto top surface contact point is also present at the top surface TDIcontact point and the bottom surface TDO contact point. If the Fuse14021 is opened, the data shifted to top surface contact point is notpresent at the top surface TDI contact point and the bottom surface TDOcontact point.

FIG. 15 illustrates a stack die example including a bottom die 1300, amiddle die 1400 and a top die 1400. This example illustrates how theTAPs 1002 of the die in the stack are accessed, according to thedisclosure. As seen, the Fuse 1402 of the middle die 1400 has beenopened to allow the die to operate as a middle die in the stack, and theFuse 1402 of the top die 1400 remains closed to allow the die to operateas the top die in the stack.

When an instruction is loaded into the bottom die to allow access to theImproved TAP of the bottom die 1300, the Improved TAP will respond tothe TCK and TMS control signals of the TCI bus to input data from thebottom surface TDI contact point and output data to the bottom surfaceTDO contact point via multiplexer 1304. As described in FIG. 14, theinstruction controls the gating circuit to gate off the TCI controlsignals to the TAPs of the upper die, and also controls multiplexer 1304to couple the TDO output of the Improved TAP of the bottom die to thebottom surface TDO contact point.

When an instruction is loaded into the bottom die to allow daisy-chainedaccess to the Improved TAPs of the bottom, middle and top die, theImproved TAPs will respond to the TCK and TMS control signals of the TCIbus to input data from the TDI contact point on the bottom surface ofthe bottom die and output data to the TDO contact point on the bottomsurface of the bottom die via multiplexer 1304. As described in FIG. 14,the instruction loaded into the bottom die controls the gating circuitto gate on the TCI control signals to the TAPs of the upper die, andalso controls multiplexer 1304 to couple the TDO output of the top dieto the bottom surface TDO contact point of the bottom die, via the TDOTSV signal path in the die stack. As seen in FIG. 15, the Fuse 1402 ofthe middle die is opened, allowing the closed Fuse 1402 of the top dieto pass the TDO output of the TAP of the top die to the bottom surfaceTDO output of the bottom die, via multiplexer 1304.

FIG. 16 illustrates a stack die example including a bottom die 1300, amiddle die 1400 and a top die 1400. This example illustrates how theparallel test circuits 1004 of each die in the stack are accessed,according to the disclosure. This description assumes the die TAPs aredaisy-chained as described in FIG. 15, to allow instructions to beloaded in all the die TAPs.

When an instruction is loaded into a TAP 1002 of one of the die, i.e.the top, middle or bottom die, to enable a parallel test circuit in thatdie, the buffers 1302 associated with that parallel test circuit areenabled to drive the PTDO TSV bus of the die stack. The parallel testcircuit receives DRC control from the TAP to input parallel data fromthe PTDI TSV bus of the stack and output parallel data to the PTDO TSVbus of the stack. The parallel test circuit may be controlled to performcapture and shift test operations or it may be controlled to performcapture, shift and update test operations, as previously describe inFIGS. 13A and 14. As seen, only the selected parallel test circuit 1004is enabled to drive the PTDO TSV bus. This test process is repeated foreach parallel test circuit 1004 to be tested in each die of the stack.

FIG. 17 illustrates an alternate embodiment of the test architecture ofthe disclosure designed into a die 1700 that is to be used as the bottomdie in a 3D stack die arrangement. The test architecture is identical tothe test architecture described in FIG. 13A, with the exceptions that(1) the buffers 1302 associated with each parallel test circuit in FIG.13A have been replaced with a test circuit (TC) 1702 and (2) the N widePTDO TSV bus of FIG. 13A has been replaced with a N+1 parallel test datainput/output (PTDIO) TSV bus.

FIG. 18 illustrates an example implementation of TC 1702. The TCincludes a plurality of buffer 1302 and comparator 1802 arrangements1808 connected as shown. Each arrangement has an input coupled to a PTDOof a parallel test circuit 1004 and an input/output coupled to a TSV onthe N+1 PTDIO TSV bus. The buffers 1302 have an input coupled to a PTDOof the parallel test circuit, an ENA1 signal from the TAP IRO bus and anoutput coupled to a PTDIO of the N+1 PTDIO TSV bus. The comparators 1802have an input coupled to a PTDO of the parallel test circuit, an inputcoupled to a PTDIO of the N+1 PTDIO TSV bus, an ENA2 signal input fromthe TAP IRO bus and a Fail output signal. Each Fail output signal isinput to an OR gate 1804. The output of the OR gate is input to a3-state buffer 1806 which, when enabled by ENA2, outputs a Compare FailOutput (CFO) signal to a TSV on the N+1 PTDIO TSV bus. Each TC willreceive a unique set of ENA1 and ENA2 control signals from the IRO. TheTC 1702 can be enabled to operate in the following two modes.

Mode 1—When the ENA1 signal is asserted, the buffers 1302 are enabled tooutput test data from a parallel test circuit to the PTDIO TSV busexactly as described in regard to FIG. 13A. A tester coupled to thePTDIO contact points of die 1700 inputs the data for analysis.

Mode 2—When the ENA2 signal is asserted, the comparators 1802 areenabled to compare the data output from a parallel test circuit to datafrom the PTDIO TSV bus. A tester coupled to the PTDIO contact points ofdie 1700 inputs the compare data. If a mismatch between the data isdetected, the comparators output a Fail signal to gate 1804, whichforwards the Fail signal to the CFO signal in the PTDIO TSV bus, whichis coupled to the tester via a PTDIO contact point on die 1700.

Testing die 1700 using Mode 1 requires the tester to have a unique PTDIObus connection to each die 1700 being tested in parallel. For example,if the PTDIO bus is 32 bits wide and 16 die 1700 are being tested inparallel, the tester has to have 512 PTDIO connections to the die.

Testing die 1700 using Mode 2 allows the tester to only have one PTDIOconnection to each die 1700 being tested in parallel. Reusing theexample above, if the PTDIO bus is 32 bits wide and 16 die 1700 arebeing tested in parallel, the tester only has to have a 32 bit widePTDIO connection to the die, plus 16 CRO connections, one from each die.

The advantage of Mode 2 therefore is that it reduces the number ofconnections between a tester and plural die being tested in parallel.This reduction of connections is beneficial at wafer level testing wherelower cost testers and probe mechanisms can be used.

FIG. 19 is provided to illustrate that comparator 1802 may include acompare (CMP) circuit that compares PTDO data from a parallel testcircuit against expected data from the PTDIO TSV bus.

FIG. 20 is provided to illustrate that comparator 1802 may include amaskable compare (MSK CMP) circuit that only compares PTDO data from aparallel test circuit against unmasked expected data from the PTDIO TSVbus. This comparator 1802 circuit is useful when the PTDO data from aparallel test circuit contains don't care or unknown data outputs thatcan generate false Fail signal outputs.

FIG. 21 is provided to illustrate TCs 1702 being used in die 2100designed for use as a middle die or top die in a die stack.

FIG. 22 is provided to illustrate a stack die example including a bottomdie 1700, a middle die 2100 and a top die 2100, each die including TCs1702.

FIG. 23 illustrates a die 2300 including the test architecture of thedisclosure wherein the parallel test circuit 1004 is realized as a scancompression circuit having a decompressor (D), parallel scan paths and acompaction circuit (C) controlled by the DRC bus from TAP 1002. Dottedline circuit box 2302 could be either buffers 1302 or TCs 1702.

FIG. 24 illustrates a die 2400 including the test architecture of thedisclosure wherein the parallel test circuit 1004 is realized asparallel scan paths controlled by the DRC bus from TAP 1002. Dotted linecircuit box 2302 could be either buffers 1302 or TCs 1702.

FIG. 25 illustrates a die 2500 including the test architecture of thedisclosure wherein the parallel test circuit 1004 is realized as an IEEE1500 core wrapper having a wrapper boundary register (WBR) and parallelscan paths controlled by the DRC bus of TAP 1002. In this example theWBR is connected as one of the TAP data register to allow it to beaccessed from TDI to TDO. Dotted line circuit box 2302 could be eitherbuffers 1302 or TCs 1702.

Today it is very common for a die to include one or more additionalTAPs, instead of just the single die TAP 1002 shown in the previousFigures. For example, there may be a TAP on each embedded intellectualproperty (IP) circuit or core in the die. FIGS. 26 and 27 belowillustrate how the disclosure can be expanded to accommodate multipleTAP in a die.

FIG. 26 illustrates an example TAP Domain architecture 2600 thatsupports access to the die ITAP 1002 alone or access to the die ITAP1002 and multiple embedded IP TAPs 2604. The IP TAPs may be conventionalTAPs 100 or they may be Improved TAPs 1002. As seen the architectureincludes the die ITAP 1002, one or more IP TAPs 2604, a TDO multiplexer2606 and gating circuitry 2608 all connected as shown. The die ITAP 1002outputs the IRO bus from the TAP Domain 2600 and control signals tomultiplexer 2606 and gating circuit 2608. Gating circuit 2608 may be anyof the previously described gating circuits of FIG. 13B-13E. At power upof following a test reset, the IRO bus disables the gating circuit frompassing TCI signals to the IP TAPs and controls the multiplexer toselect the TDO output of the die ITAP to be output on TDO of the TAPDomain. In this configuration and during instruction and data scanoperations, the die ITAP operates alone to shift data from the TDI inputof the TAP Domain to the TDO output of the TAP Domain via multiplexer2606. Since the TCI inputs to the IP TAPs are gated off they do notrespond to the instruction and data scan operations.

When it is required to access the IP TAPs 2604, an instruction isscanned into the die ITAP to output control on the IRO bus to enable thegating circuit 2608 and control the multiplexer to input the TDO fromthe one or more IP TAPs. After this instruction is loaded, the die ITAPand the one or more IP TAPs all shift data from the TDI input of the TAPDomain to the TDO output of the TAP Domain during instruction and scanoperations. After access to the IP TAPs is complete, another instructionis scanned into the die ITAP to disable the gating circuit and controlthe multiplexer to select the TDO output of the Die ITAP to be output onthe TDO output of the TAP Domain.

FIG. 27 illustrates a stack die example including a bottom die 2706, amiddle die 2704 and a top die 2702. This example illustrates how the TAPDomains 2600 of the die in the stack are accessed, according to thedisclosure. The access is the same as the access described in FIG. 15with the exception that multiple TAPs existing in the TAP Domain 2600 ofeach die may be accessed instead of just the single die ITAP 1002.

It is important to note that the bottom and top surface test contactpoints of one die in this disclosure are shown to line up with bottomand top surface test contact points of another other die in thisdisclosure. This is intentional and facilitates the die stackingprocess. If they did not line up, an interposer (redistribution layer)would have to be used between each die in the stack to form theconnections between the test contact points.

Although the disclosure has been described in detail, it should beunderstood that various changes, substitutions and alterations may bemade without departing from the spirit and scope of the disclosure asdefined by the appended claims.

What is claimed is:
 1. An integrated circuit comprising: (a) a test datain lead, a test clock lead, a test mode select lead, a test data outlead, and an update lead; (b) a TAP state machine having a clock inputcoupled to the test clock lead, a mode input coupled to the test modeselect lead, data register control outputs that include a ClockDR signaland an UpdateDR signal, and instruction register control outputs; (c) aninstruction register having a test data input coupled to the test datain lead, instruction register control inputs coupled to the instructionregister control outputs, and instruction register outputs; (d) dataregisters having test data inputs coupled to the test data in lead, dataregister control inputs, and instruction register control inputs coupledto the instruction register outputs; and (e) dual port router circuitryhaving: (i) first multiplexer circuitry having an input connected to theupdate lead, an input connected to the UpdateDR signal, a control inputconnected to one of the instruction register outputs, and an output;(ii) first gating circuitry having an input connected to the output ofthe multiplexer circuitry, an input connected to the control input ofthe first multiplexer circuitry, and a gated UpdateDR signal outputcoupled to a data register control input of the data registers.
 2. Theintegrated circuit of claim 1 in which each of the instruction registerand the data registers have a test data output, and including a secondmultiplexer having an input for each test data output, and an outputcoupled to the test data out lead.
 3. The integrated circuit of claim 1in which each of the instruction register and the data registers have atest data output, and the state machine has a select output, andincluding a second multiplexer having a select input coupled to theselect output, instruction register inputs coupled to the instructionregister outputs, an input for each test data output, and an outputcoupled to the test data out lead.
 4. The integrated circuit of claim 1in which the dual port router circuitry includes second gating circuitryhaving an input connected to the ClockDR signal, an input connected tothe control input of the first multiplexer circuitry, and a gatedClockDR signal output coupled to a data register control input of thedata registers.